Aminothiazolyl coumarin derivatives as effectual inhibitors to alleviate corrosion on mild steel in 0.5 M H2SO4

To diminish corrosion which leads to structural damages and to implement a green mitigator has induced the usage of aminothiazolyl coumarin derivatives to study mild steel (MS) corrosion using potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), weight loss, atomic force microscopy (AFM), and electron microscopy with energy dispersive spectroscopy (SEM–EDS) spectrometry in acid medium. The results showed that the inhibition efficiency was 90.8% for the least effective inhibitor and 97.1% for the most effective inhibitor at optimal concentration (10 mM). Enhancement of inhibition efficiency in weight loss method and increase in Rp values in impedance and mixed nature of the inhibition in polarization measurement reveals the best inhibition capacity of coumarins over the MS. The coumarins were characterized using FT-IR, NMR and Mass spectroscopy. The adsorption was well fitted with the Langmuir adsorption isotherm model. SEM–EDS and AFM images confirmed the shielding effect of coumarin derivatives through a layer formation on MS against acid medium. The adsorption mechanism of aminothiazolyl coumarin derivatives was further explored by quantum chemical calculations (DFT) and molecular dynamics (MD).